181 research outputs found
Faster all-pairs shortest paths via circuit complexity
We present a new randomized method for computing the min-plus product
(a.k.a., tropical product) of two matrices, yielding a faster
algorithm for solving the all-pairs shortest path problem (APSP) in dense
-node directed graphs with arbitrary edge weights. On the real RAM, where
additions and comparisons of reals are unit cost (but all other operations have
typical logarithmic cost), the algorithm runs in time
and is correct with high probability.
On the word RAM, the algorithm runs in time for edge weights in . Prior algorithms used either time for
various , or time for various
and .
The new algorithm applies a tool from circuit complexity, namely the
Razborov-Smolensky polynomials for approximately representing
circuits, to efficiently reduce a matrix product over the algebra to
a relatively small number of rectangular matrix products over ,
each of which are computable using a particularly efficient method due to
Coppersmith. We also give a deterministic version of the algorithm running in
time for some , which utilizes the
Yao-Beigel-Tarui translation of circuits into "nice" depth-two
circuits.Comment: 24 pages. Updated version now has slightly faster running time. To
appear in ACM Symposium on Theory of Computing (STOC), 201
Rituximab Not Effective for Hearing Loss in Coganâs Syndrome
Importance. Rituximab was not effective in ameliorating the hearing loss in a patient with atypical Coganâs syndrome. Observations. We report the case of a patient who developed acute bilateral uveitis and sensorineural hearing loss. A diagnosis of atypical Coganâs syndrome was made. The patientâs hearing loss did not improve despite high dose steroids and azathioprine. Rituximab was administered given a recent report of its efficacy in a patient with refractory disease; however, our patientâs hearing loss did not improve. Conclusion. Hearing loss in Coganâs syndrome is difficult to treat. Though rituximab was ineffective in our case, earlier administration in the disease course could be effective for future patients
An Ecological Approach to Understanding Program Management Practices for Food Pantries in Rural Communities
This qualitative study was conducted in Mississippi, a state comprised of 82 counties, many of which are rural and highly impoverished. To gain a greater understanding of the food needs of residents from across the state, a representative sample of food pantries from each region of the state was identified. For this project, researchers with the Mississippi Food Insecurity Project formed a partnership with the Mississippi Food Network to interview partner pantries across the state. Interviews were conducted with food pantry managers and volunteers to examine various issues, challenges, and successes related to their operations. All interviews were transcribed and coded using a systematic analysis of codes to generate major themes related to pantry management protocols. Using an ecological framework, our study yielded five major areas of consideration for optimal pantry management: volunteer recruitment, operating and control systems, patron needs, collaboration, and advocacy
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Young Adult Outcomes Associated with Teen Pregnancy Among High-Risk Girls in an RCT of Multidimensional Treatment Foster Care
Teen pregnancy is associated with a host of deleterious outcomes for girls such as drug use and poor parenting. Thus, reducing teen pregnancy rates could improve long-term developmental outcomes for girls, improving adjustment during young adulthood. Based on the positive effects of Multidimensional Treatment Foster Care (MTFC) relative to group care (GC) in a study of adolescent girlsâsignificantly fewer pregnancies reported in the 2-year follow-up for MTFC girlsâthe present study followed this sample into young adulthood (approximately 7 years post-baseline) to examine the effects of adolescent pregnancy on young adult substance use and pregnancy-related outcomes. All participants were randomly assigned to MTFC (n = 81) or GC (n = 85) as adolescents as part of two RCTs. Results from logistic regression analyses indicated that becoming pregnant during the 2-year follow-up was significantly related to illicit drug use, miscarriage from a new pregnancy, and child welfare involvement at 7 years post-baseline. In addition, baseline marijuana use predicted marijuana use at 7 years post-baseline.Keywords: juvenile justice, young adulthood, teen pregnancy, RCT, drug us
Interpreting the Biological Effects of Protons as a Function of Physical Quantity: Linear Energy Transfer or Microdosimetric Lineal Energy Spectrum?
The choice of appropriate physical quantities to characterize the biological effects of ionizing radiation has evolved over time coupled with advances in scientific understanding. The basic hypothesis in radiation dosimetry is that the energy deposited by ionizing radiation initiates all the consequences of exposure in a biological sample (e.g., DNA damage, reproductive cell death). Physical quantities defined to characterize energy deposition have included dose, a measure of the mean energy imparted per unit mass of the target, and linear energy transfer (LET), a measure of the mean energy deposition per unit distance that charged particles traverse in a medium. The primary advantage of using the dose and LET physical system is its relative simplicity, especially for presenting and recording results. Inclusion of additional information such as the energy spectrum of charged particles renders this approach adequate to describe the biological effects of large dose levels from homogeneous sources. The primary disadvantage of this system is that it does not provide a unique description of the stochastic nature of radiation interactions. We and others have used dose-averaged LET (LE
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Juvenile Justice Girlsâ Depressive Symptoms and Suicidal Ideation 9 Years After Multidimensional Treatment Foster Care
OBJECTIVE: Multidimensional Treatment Foster Care (MTFC) has been found to reduce delinquency among girls in juvenile justice through 2-year follow-up. Given that such girls are at elevated risk for suicide and depression into adulthood, we tested MTFC effects on long term trajectories of suicidal ideation and depressive symptoms.
METHOD: Girls [n =166; mean (SD) age = 15.3 (1.2) years; 68% Caucasian] with a recent criminal referral who were mandated to out-of-home care were enrolled in two sequential cohorts. Girls were randomized to receive MTFC (n = 81) or group care (GC) treatment as usual (TAU; n = 85); the second MTFC cohort also received modules targeting substance use and risky sexual behavior. Depressive symptoms and suicidal ideation were assessed repeatedly through early adulthood [mean (SD) follow-up = 8.8 (2.9) years]. Suicide attempt history was assessed in early adulthood.
RESULTS: Girls assigned to MTFC showed significantly greater decreases in depressive symptoms across the long-term follow-up than GC girls (Ï = -.86, p < .05). Decreases in suicidal ideation rates were slightly stronger in MTFC than in GC as indicated by a marginal main effect [odds ratio (OR) = .92, p < .10] and a significant interaction that favored MTFC in the second cohort relative to the first [OR = .88, p < .01]. There were no significant MTFC effects on suicide attempt.
CONCLUSIONS: MTFC decreased depressive symptoms and suicidal thinking beyond the decreases attributable to time and TAU. Thus, MTFC has further impact on girlsâ lives than originally anticipated.This article may not exactly replicate the final version published in the APA journal. It is not the copy of record. This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by the American Psychological Association and can be found at: http://www.apa.org/pubs/journals/ccp/Keywords: Juvenile justice, MTFC, Depression, Suicide, Randomized controlled trial, RC
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Young Adult Follow-up of Adolescent Girls in Juvenile Justice Using the Columbia Suicide Severity Rating Scale
We studied the reliability and validity of the Columbia Suicide Severity Scale (C-SSRS).
Severely delinquent adolescent girls (n = 166) participated in a treatment trial and repeated
assessments over time. Lifetime suicide attempt history was measured using the C-SSRS in early
adulthood (n = 144; 7â12 years post-baseline). Nonclinician raters showed strong interrater
reliability using the C-SSRS. Self-, caseworker-, and caregiver-reports of girlsâ suicide attempt
histories collected at baseline correlated with adult participantsâ recollections of their baseline
attempt histories. Suicidal ideation measured prospectively across a 7â12 year period was
associated with retrospectively reported suicide attempt across the same period
Young adult outcomes associated with teen pregnancy among high-risk girls in a randomized controlled trial of Multidimensional Treatment Foster Care
Teen pregnancy is associated with a host of deleterious outcomes for girls, such as drug use and poor parenting. Thus, reducing teen pregnancy rates could improve long-term developmental outcomes for girls, including adjustment during young adulthood. Based on the positive effects of Multidimensional Treatment Foster Care (MTFC) relative to group care (GC) in a study of adolescent girls (significantly fewer pregnancies reported in the 2-year follow-up for MTFC girls), the present study followed this sample into young adulthood (approximately 7 years post-baseline) to examine the effects of adolescent pregnancy on young adult substance use and pregnancy-related outcomes. All participants were randomly assigned to MTFC (N = 81) or GC (N = 85) as adolescents as part of a randomized controlled trial (RCT). Results from logistic regression analyses indicated that becoming pregnant during the 2-year follow-up was significantly related to illicit drug use, miscarriage from a new pregnancy, and child welfare involvement 7 years post-baseline. In addition, baseline marijuana use predicted marijuana use at 7 years post-baseline. © 2013 Copyright Taylor and Francis Group, LLC
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Depressive Symptom Trajectories Among Girls in the Juvenile Justice System: Findings from an RCT of Multidimensional Treatment Foster Care
Youth depression is a significant and growing international public health problem. Youth who engage in high levels of delinquency are at particularly high risk for developing problems with depression. The present study examined the impact of a behavioral intervention designed to reduce delinquency (Multidimensional Treatment Foster Care; MTFC) compared to a group care intervention (GC; i.e., services as usual) on trajectories of depressive symptoms among adolescent girls in the juvenile justice system. MTFC has documented effects on preventing girlsâ recidivism, but its effects on preventing the normative rise in girlsâ depressive symptoms across adolescence have not been examined. This indicated prevention sample included 166 girls (13â17 years at T1) who had at least one criminal referral in the past 12 months and who were mandated to out-of-home care; girls were randomized to MTFC or GC. Intent-to-treat analyses examined the main effects of MTFC on depression symptoms and clinical cut-offs, and whether benefits were greatest for girls most at risk. Depressive symptom trajectories were specified in hierarchical linear growth models over a two year period using five waves of data at six month intervals. Depression clinical cut-off scores were specified as nonlinear probability growth models. Results showed significantly greater rates of deceleration for girls in MTFC versus GC for depressive symptoms and for clinical cut-off scores. The MTFC intervention also showed greater benefits for girls with higher levels of initial depressive symptoms. Possible mechanisms of effect are discussed, given MTFCâs effectiveness on targeted and nontargeted outcomes.This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/11121.Keywords: randomized controlled trial, juvenile justice, maltreatment, MTFC (Multidimensional Treatment Foster Care), girls, depressio
Structure of Complement Component C2a: Implications for Convertase Formation and Substrate Binding
SummaryC2a provides the catalytic center to the convertase complexes of the classical and lectin-binding pathways of complement activation. We determined two crystal structures of full-length C2a, with and without a pseudo ligand bound. Both structures reveal a near-active conformation of the catalytic center of the serine protease domains, while the von Willebrand factor A-type domains display an intermediate activation state of helix α7 with an open, activated metal-ion-dependent adhesion site. The open adhesion site likely serves to enhance the affinity for the ligand C4b, similar to âinside-outâ signaling in integrins. Surprisingly, the N-terminal residues of C2a are buried in a crevice near helix α7, indicative of a structural switch between C2 and C2a. Extended loops on the protease domain possibly envelop the protruding anaphylatoxin domain of the substrate C3. Together with a putative substrate-induced completion of the oxyanion hole, this may contribute to the high substrate specificity of the convertases
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